A friend of mine phoned me up last night asking for a bit of advice on her 18-year-old cat. She said he has started howling like a dog at nights (friend said she was terrified at one point because she was awoken and thought it actually was a dog!) and he's also taken to peeing behind the TV and on freshly washed towels.
I told her I think it could possibly be cat dementia and all due to his relatively older age. But I also said I'd ask you all on the forum too as you always give valuable information and help.